/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.tomcat.util.descriptor;

import org.apache.juli.logging.Log;
import org.apache.juli.logging.LogFactory;
import org.apache.tomcat.util.digester.Digester;
import org.apache.tomcat.util.digester.RuleSet;
import org.apache.tomcat.util.res.StringManager;
import org.xml.sax.ext.EntityResolver2;

import javax.servlet.ServletContext;
import java.net.URL;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;

/**
 * Wrapper class around the Digester that hide Digester's initialization
 * details.
 */
public class DigesterFactory {

	/**
	 * Mapping of well-known public IDs used by the Servlet API to the matching
	 * local resource.
	 */
	public static final Map<String, String> SERVLET_API_PUBLIC_IDS;
	/**
	 * Mapping of well-known system IDs used by the Servlet API to the matching
	 * local resource.
	 */
	public static final Map<String, String> SERVLET_API_SYSTEM_IDS;
	private static final Log log = LogFactory.getLog(DigesterFactory.class);
	private static final StringManager sm =
			StringManager.getManager(Constants.PACKAGE_NAME);
	private static final Class<ServletContext> CLASS_SERVLET_CONTEXT;
	private static final Class<?> CLASS_JSP_CONTEXT;

	static {
		CLASS_SERVLET_CONTEXT = ServletContext.class;
		Class<?> jspContext = null;
		try {
			jspContext = Class.forName("javax.servlet.jsp.JspContext");
		} catch (ClassNotFoundException e) {
			// Ignore - JSP API is not present.
		}
		CLASS_JSP_CONTEXT = jspContext;
	}

	static {
		Map<String, String> publicIds = new HashMap<String, String>();
		Map<String, String> systemIds = new HashMap<String, String>();

		// W3C
		add(publicIds, XmlIdentifiers.XSD_10_PUBLIC, locationFor("XMLSchema.dtd"));
		add(publicIds, XmlIdentifiers.DATATYPES_PUBLIC, locationFor("datatypes.dtd"));
		add(systemIds, XmlIdentifiers.XML_2001_XSD, locationFor("xml.xsd"));

		// from J2EE 1.2
		add(publicIds, XmlIdentifiers.WEB_22_PUBLIC, locationFor("web-app_2_2.dtd"));
		add(publicIds, XmlIdentifiers.TLD_11_PUBLIC, locationFor("web-jsptaglibrary_1_1.dtd"));

		// from J2EE 1.3
		add(publicIds, XmlIdentifiers.WEB_23_PUBLIC, locationFor("web-app_2_3.dtd"));
		add(publicIds, XmlIdentifiers.TLD_12_PUBLIC, locationFor("web-jsptaglibrary_1_2.dtd"));

		// from J2EE 1.4
		add(systemIds, "http://www.ibm.com/webservices/xsd/j2ee_web_services_1_1.xsd",
				locationFor("j2ee_web_services_1_1.xsd"));
		add(systemIds, "http://www.ibm.com/webservices/xsd/j2ee_web_services_client_1_1.xsd",
				locationFor("j2ee_web_services_client_1_1.xsd"));
		add(systemIds, XmlIdentifiers.WEB_24_XSD, locationFor("web-app_2_4.xsd"));
		add(systemIds, XmlIdentifiers.TLD_20_XSD, locationFor("web-jsptaglibrary_2_0.xsd"));
		addSelf(systemIds, "j2ee_1_4.xsd");
		addSelf(systemIds, "jsp_2_0.xsd");

		// from JavaEE 5
		add(systemIds, XmlIdentifiers.WEB_25_XSD, locationFor("web-app_2_5.xsd"));
		add(systemIds, XmlIdentifiers.TLD_21_XSD, locationFor("web-jsptaglibrary_2_1.xsd"));
		addSelf(systemIds, "javaee_5.xsd");
		addSelf(systemIds, "jsp_2_1.xsd");
		addSelf(systemIds, "javaee_web_services_1_2.xsd");
		addSelf(systemIds, "javaee_web_services_client_1_2.xsd");

		// from JavaEE 6
		add(systemIds, XmlIdentifiers.WEB_30_XSD, locationFor("web-app_3_0.xsd"));
		add(systemIds, XmlIdentifiers.WEB_FRAGMENT_30_XSD, locationFor("web-fragment_3_0.xsd"));
		addSelf(systemIds, "web-common_3_0.xsd");
		addSelf(systemIds, "javaee_6.xsd");
		addSelf(systemIds, "jsp_2_2.xsd");
		addSelf(systemIds, "javaee_web_services_1_3.xsd");
		addSelf(systemIds, "javaee_web_services_client_1_3.xsd");

		SERVLET_API_PUBLIC_IDS = Collections.unmodifiableMap(publicIds);
		SERVLET_API_SYSTEM_IDS = Collections.unmodifiableMap(systemIds);
	}

	private static void addSelf(Map<String, String> ids, String id) {
		String location = locationFor(id);
		if (location != null) {
			ids.put(id, location);
			ids.put(location, location);
		}
	}

	private static void add(Map<String, String> ids, String id, String location) {
		if (location != null) {
			ids.put(id, location);
		}
	}

	private static String locationFor(String name) {
		URL location = CLASS_SERVLET_CONTEXT.getResource("resources/" + name);
		if (location == null && CLASS_JSP_CONTEXT != null) {
			location = CLASS_JSP_CONTEXT.getResource("resources/" + name);
		}
		if (location == null) {
			log.warn(sm.getString("digesterFactory.missingSchema", name));
			return null;
		}
		return location.toExternalForm();
	}

	/**
	 * Create a <code>Digester</code> parser.
	 *
	 * @param xmlValidation     turn on/off xml validation
	 * @param xmlNamespaceAware turn on/off namespace validation
	 * @param rule              an instance of <code>RuleSet</code> used for parsing the xml.
	 * @param blockExternal     turn on/off the blocking of external resources
	 */
	public static Digester newDigester(boolean xmlValidation,
	                                   boolean xmlNamespaceAware,
	                                   RuleSet rule,
	                                   boolean blockExternal) {
		Digester digester = new Digester();
		digester.setNamespaceAware(xmlNamespaceAware);
		digester.setValidating(xmlValidation);
		digester.setUseContextClassLoader(true);
		EntityResolver2 resolver = new LocalResolver(SERVLET_API_PUBLIC_IDS,
				SERVLET_API_SYSTEM_IDS, blockExternal);
		digester.setEntityResolver(resolver);
		if (rule != null) {
			digester.addRuleSet(rule);
		}

		return digester;
	}
}
